#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    int peakIndexInMountainArray(vector<int>& arr) {

        int left = 1;
        int right = arr.size() - 2;

        while (left < right)
        {
            int mid = left + (right - left + 1) / 2;

            if (arr[mid] > arr[mid - 1])
            {
                left = mid;
            }
            else
            {
                right = mid - 1;
            }
        }

        return left;

    }
};